1. Field of the Invention
The present invention relates to a display panel technology, and more particularly, to a defect detection method for a display panel based on histogram of oriented gradient.
2. Description of Prior Art
With a rapid development of display technology, defect detection on display panels during each manufacturing process is an inevitable procedure in order to assure and improve the display panel yield rate. The display panel manufacture is complicated. There are various types of defects such as short circuit, break circuit, mura, and foreign matter. Currently, detection on TFT-LCD defects primarily includes human visual inspection, automatic visual inspection, and electrical parameter detection. The human visual inspection has a problem of lower efficiency and erroneous recognition due to judgment of perceptual experience and fatigue. Therefore, developing the automatic visual inspection is an effective way to meet the requirements of rapidly developed TFT-LCD industrial inspection.
The automatic visual inspection combines computer image process and model recognition based on machine vision technology. Its primary concept is collecting an image of a to-be-detected object and extracting valuable information from the image for proceeding with model recognition and classification, thereby carrying out defect detection and determination. Since machine visual detection has wide application scope and is accurate, effective, and reliable, it has received considerable attention in modern industrial detection.
For example, the machine visual detection applied to defect detection on liquid crystal display panels presently includes a two-dimensional DWT algorithm, a sub-image-based singular value decomposition, a defect feature information extraction combining one-dimensional Fourier transformation and full scale wavelet transform, and an image segmentation algorithm based on Chan-Vese model. However, the automatic inspection based on machine vision cannot have detection accuracy and speed at the same time, thereby affecting the improvements of capacity of production for the display panels.